As mentioned, Core 2 Extreme QX6700 has four cores and runs internally at 2.66 GHz. As you can see the only difference on its name is the letter ”Q“, standing for quad-core. Newer quad-core CPUs to be released in the beginning of 2007 will be called Core 2 Quad.

Internally this CPU has two Core 2 Duo chips. So you can think of Core 2 Extreme QX6700 as being two Core 2 Duo E6700 chips. Since it has two separated chips inside, its 8 MB L2 memory cache isn’t unified as it occurs with Core 2 Duo processors. In fact it has two 4 MB L2 memory caches, the first one is shared by cores 1 and 2 and the second one is shared by cores 3 and 4.

Externally it keeps using socket LGA775 and 1,066 MHz front side bus (FSB), so you can install Core 2 Extreme QX6700 on any socket LGA775 motherboard that supports Core 2 Duo CPUs (however a BIOS upgrade may be necessary).

The system recognizes Core 2 Extreme QX6700 as four independent CPUs. Keep in mind that each CPU core is a real physical CPU and not a simulation like Hyper-Threading technology. By the way, Core 2 CPUs don’t have Hyper-Threading technology; this technology – at least so far – is exclusive of NetBurst microarchitecture, which is used by Pentium 4 and Pentium D (dual-core version of Pentium 4) processors. Core 2 CPUs use a new microarchitecture, called Core microarchitecture, which is based on Pentium M’s (which, in turn, is based on Pentium III’s).